HPLC technology is widely used to detect and identify different components contained in a test sample. Typical HPLC instruments use a high pressure pump for forcing a suitable mobile phase, via capillary lines, at a constant flow rate serially through an autosampler, a separation column and a UV or other type detector. The column contains an absorbent selected for the components anticipated to be in the test samples. For instigating a run, a small quantity of the test sample is introduced into the mobile phase by an injector to travel through the separation column. The different sub phase sample components pass through the column at different rates, each thereby becoming substantially isolated before passing the detector for individual identification.
When test samples include undesirable matrices, the sample needs to be cleaned. The usual way of cleaning involves filtration, centrifugation, precipitation, or absorption of matrices prior to the introduction of the sample into the HPLC system. Alternatively, the direct way to achieve cleaning is to include in the HPLC flow schematic a guard column located upstream of the separation column, operable to trap out matrices from flowing into and blocking the separation column, which would dramatically shorten its useful separation life. The guard column is inexpensive compared to the separation column, and is expected to be replaced frequently. However, replacement of the guard column is not without significance, as it must include both the cost of the new guard column and the down time of the HPLC system while installing it.